If the pay of the officers posted on deputation to the Central Government under Central Staffing Scheme, after fixation in the revised pay structure either under these rules or as per the instructions regulating such fixation of pay on the post to which they are appointed on deputation, happens to be lower than the pay these officers would have been entitled to, had they been in their parent cadre and would have drawn that pay but for the Central deputation, such difference in the pay shall be protected in the form of Personal Pay with effect from the date of notification of these rules